Silver Nanoparticles: From Bulk Material to Colloidal Nanoparticles

Abstract

Metals exhibit interesting optical properties, especially in comparison to molecules and semiconductors. In contrast to molecules and semiconductors, metals support plasmons, which are a collective oscillation of many electrons in the material. When the size of these metal nanoparticles is small (<100 nm), these plasmon absorbances occur in the visible region of the electromagnetic spectrum, giving rise to colored solutions. One of the unique characteristics of plasmon excitation is the conversion of light energy into extreme and highly localized heating at the surface of these particles. Excitation of plasmons by both pulsed (i.e. lasers) and continuous (i.e. sunlight) excitation and the effects of plasmon excitation on the surrounding material are discussed in this chapter. The potential for using these materials in photothermal therapy for ailments such as cancer is also discussed in terms of the unique properties of these metals, related to plasmon excitation.